A square-shaped steel member, which is used in the lightweight steel field, generally adopts a square-shaped steel tube or two C-shaped steel members welded together. Ordinary tacking holes for bolting with other members in present square-shaped steel tube could only be made with a driller or flame and hence cannot be punched and processed with a press machine, thereby causing the cost to be high. The present square-shaped steel tube cannot be engaged with other member with a friction-type high-tension bolt, thus greatly reducing bearing capacity of a joint. As shown in FIG. 1, the figure shows the combination of present steel tube member used in the prior art. As to the member, the square-shaped steel, which is molded through a welding method, is used and taken as the main body structure 7. When used, the member is connected with a C-shaped steel 6 by a common bolt. Therefore, the square-shaped steel will be deformed because of too big shearing force. For corrosion resisting, the square-shaped steel tube is generally coated after being processed, which causes the cost to be high. If the tube was welted together by galvanized C-shaped steel, the process of welting will hurt the coating of corrosion resisting layer.
Therefore, the abovementioned present square-shaped steel member still has some shortcoming in actual application, which is rather urgent to implement further breakthrough improvement. In order to solve the present problems of the present lightweight square-shaped steel member, the inventor, based on the rich and practical experience in the design and manufacture of such products for many years as well as matching the applications of theories, actively carries out research and innovation, so as to create a novel square-shaped lightweight steel member with reinforced components which may improve the general present square-shaped lightweight steel member and facilitates it to have further practicability. Through continuous research, design, repeated trials and improvement, the inventor finally creates the invention which is indeed useful and practical.